This invention relates in general to the detection of relatively small temperature differentials or variations over selected regions of living tissue and more particularly to an improvement in the application of an elastomeric film containing cholesteric liquid crystals to the surface of the selected region of the body.
Techniques and apparatus for employing elastomer sheets of cholesteric liquid crystals (hereinafter generally liquid crystals) are described in the U.S. Pat. No. 4,135,497 issued Jan. 23, 1979 and in pending patent application Ser. No. 088,159 filed Oct. 25, 1979. The disclosure of this patent and patent application are incorporated herein by reference in order to simplify the specification herein.
Experience has shown that the skin oils from the tissues being investigated tend to migrate into the elastomeric film, react with the liquid crystals and cause degradation of the product. This is a key factor in limiting the number of times that any given unit of the products involved can be used.
Accordingly, it is a major purpose of this invention to provide a technique for reducing the contamination and degradation of the liquid crystals and thereby increase the usable life of the detection apparatus involved.
However, it is important that the liquid crystals remain in intimate thermal contact with the body tissues so as to continue to display relatively slight temperature differentials. Temperature differences of somewhat less than 0.1.degree. C. can be visually identified by observing a color differential. It has been found that the least air bubble or interference with smooth continuous contact between the tissue being investigated and the elastomeric sheet will result in loss of meaningful picture over any portion of the tissue involved and/or loss of sensitivity.
Accordingly, it is important that any technique for reducing contamination be compatible with maintaining the sensitivity and reliability of the liquid crystal containing elastic sheet.